File segments generated with Vision Version 4 can be given customized extensions.
The naming rules described here do not apply to the first data segment. Set the name of the first segment as you would for any file. This name is referred to as the "regular" name of the file in this section.
Tip: Turning on file tracing level 3 or higher ("tf 3") in the debugger will display some diagnostics that show which names are being used for the various segments of a Vision Version 4 file. Also, "vutil -info" will display the names of all of the segments of a Vision Version 4 file.
Vision Version 4 employs two different methods to determine the file names of additional index and data segments (after the first segment).
The first method takes precedence over the second method. That is, if circumstances allow Vision Version 4 to use the first method, it will be used. If not, the second (default) method will be used.
In the following methods, environment variables are used to indicate how Vision Version 4 is to determine the file names of additional segments. You form the names of these environment variables by taking the base name of the file, converting all the alphabetic characters to upper case, leaving numeric characters alone, and converting all other characters to underscores ("_"). Thus, gl42.dat becomes GL42_DAT. This name is typically suffixed with another string, depending upon which method you are using, as described below. Note that the runtime looks for these variables in the runtime configuration file. Utilities such as vio and vutil look for them in the operating system's environment.